Sixteen elements are known to be essential for plant growth. Three of the elements (carbon, hydrogen, and oxygen) are provided in large amounts by carbon dioxide in the atmosphere and by water in both the atmosphere and the soil. The other thirteen essential elements are needed in varying amounts and are often added to the soil as fertilizers.
Nitrogen is one of the thirteen essential elements and is needed in relatively large amounts by crops such as corn and soybeans. Although nitrogen in the form of N2 gas makes up almost eighty percent of the gases in earth's atmosphere, plants are unable to use nitrogen gas. Instead, plants are able to use nitrogen only when it is in the form of nitrate ions (NO3−) that contact their roots in the soil.
Nitrogen is added to fertilize the soil in many different forms. In commercial farming, nitrogen is often added in the form of anhydrous (water free) ammonia (NH3). Ammonia is a gas at ambient temperatures and atmospheric pressure. If applied as a gas, the ammonia would largely dissipate before forming a solution with the water present in the soil. To prevent nearly complete dissipation, anhydrous ammonia must be applied as a liquid. This requires the anhydrous ammonia to be stored in pressurized containers, applied as a liquid into a trench, and then immediately covered with dirt. For many years, it has been common practice for corn and soybean farmers to add nitrogen to the soil once a year in the form of anhydrous ammonia.
In recent years it has been discovered that corn and soybean yields are increased by applying nitrogen to the soil at two different times: (1) before or at planting; and (2) when the plants are midway through their growth season. When the plants are growing, there are problems in applying anhydrous ammonia because a deep trench can damage the root systems of the growing plants. The formation of a deep trench can also hurl large dirt particles that damage the growing plants. Miller, U.S. Pat. No. 7,739,969, Jun. 22, 2010, discloses a side dressing shield that deflects dirt particles from damaging young corn plants. However, many farmers continue to avoid applying anhydrous ammonia to fields containing growing plants.
Nitrogen can be applied to the soil in the form of liquid solutions. Although applying nitrogen as a liquid solution is more expensive than applying as anhydrous ammonia, the liquid solutions can be added without forming a deep trench. Accordingly, it has become common to apply liquid nitrogen solutions to fields containing growing plants. The most common liquid nitrogen solutions contain a combination of urea (CO(NH2)2) and ammonium nitrate (NH4NO3) and are known as UAN (urea ammonium nitrate) fertilizers.
Liquid UAN fertilizers are commonly applied with equipment having a single hose between each row of growing plants. The liquid seeps into the ground, the nitrogen gradually converts to the nitrate form, and an effective amount eventually reaches the root systems of the plants.
From the time the UAN fertilizers are poured onto the ground between rows to the time the nitrogen actually reaches the root systems, nitrogen losses occur for four primary reasons. Some of the nitrogen is lost due to volatilization in which the liquid is dispersed into the atmosphere. Some of the nitrogen is lost due to leaching, especially if large rains occur soon after application that physically wash the nitrogen deeper into the ground beyond the root systems. Some of the nitrogen is lost to denitrification in which microbes convert the nitrogen compounds into nitrogen gas that cannot be used by the plants. And some of the nitrogen is lost to immobilization in which the nitrogen is converted to organic compounds that cannot be used by the plants.
While the loss of nitrogen from UAN fertilizers is a major problem, it is merely a part of the larger problem of inefficiencies in the delivery of all types of fertilizers. Many fertilizers are routinely applied in ways that do not optimally deliver the fertilizer to the crops. Not only does this represent an economic loss to the farmer, it often results in the fertilizer entering bodies of water and causing environmental problems.
The 360 Yield Center of Morton, Ill. manufactures and sells the 360 Y-DROP liquid fertilizer application system. The system reduces nitrogen losses and gets more of the applied nitrogen to the plant root systems. As shown in FIGS. 1 and 2, the system consists of multiple bullet shaped units that are suspended from an overhead toolbar and that pass down the rows about two feet above the ground. A hose extends outwardly and downwardly from each unit so that the ends (outlets) of the hoses drag along the ground in contact with the plants on either side. The liquid fertilizer is thus applied directly onto the bases of the plants.
Although the 360 Y-DROP system is an improvement, excessive amounts of nitrogen continue to be lost. Accordingly, there is a demand for an improved apparatus and an improved method for applying fertilizers directly to the bases of growing plants in two adjacent rows that reduces losses.